Machine tool with a manipulator

ABSTRACT

A machine tool ( 10 ) is provided with a workpiece carrier ( 19 ) for clamping a workpiece ( 18 ) to be machined and with a headstock (14) in which a rotary-driven tool spindle ( 15 ) is mounted into which tools ( 16 ) can be clamped for machining the workpieces ( 18 ). Further, a device ( 26 ) is provided for removing and holding the workpiece ( 18 ) that has been finished in the workpiece carrier ( 19 ) for further machining. The device ( 26 ) comprises a manipulator ( 27 ) for positioning a gripper ( 28 ) by which a workpiece ( 18 ) is removable that has been finished in the workpiece carrier ( 19 ), and a clamping station ( 29 ) into which the gripper ( 28 ) that holds the workpiece can be inserted (FIG.  1 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a machine tool, comprising aworkpiece carrier for clamping a workpiece to be machined, and aheadstock in which a rotary-driven tool spindle is mounted, into whichspindle tools for machining the workpieces can be clamped, as well as adevice for removing and holding for further machining the workpiece thathas been finished in the workpiece carrier.

[0003] 2. Related Prior Art

[0004] Such a machine tool is known from EP 0 368 996 B1. The knownmachine tool is a moving column machine, on the machine bed whereof aclamping device for workpiece bars is arranged. The clamping device isprovided with a rotary drive, so that a workpiece bar can be machined atall four longitudinal sides by means of a tool that is clamped into thetool spindle.

[0005] In longitudinal direction of the workpiece bar, on the machinebed a unit for gripping and pivoting is provided that is mounted on anown cross slide. As soon as the four longitudinal sides of the workpiecehave been finished, the cross slide moves towards the workpiece andclamps same into its jaw chuck. After that, the workpiece is being cutfrom the bar and the cross slide is somewhat moved back. The jaw chuckis now pivoted to the top by about 180°, so that the cut side can bemachined from the top by means of a milling tool.

[0006] With this machine, a machining of the front side opposing theseparation side is possible only in a limited way.

[0007] In order to overcome this problem, DE 196 35 258 C1 discloses acomparable machine tool, in which, however, the clamping device ispivotable about an axis that runs transversally with respect to thelongitudinal axis of the workpiece bars. In this manner, it is possibleto machine the four longitudinal sides of the workpiece and its frontside remote from the clamping device.

[0008] After these five sides have been machined, the workpiece ismostly cut from the rest of the workpiece bar by means of a circular sawthat can be clamped into the tool spindle.

[0009] After that, the clamping device is moved again into itshorizontal position, so that the unit for gripping and pivoting canadvance and grip the workpiece at the front side that has now beenmachined. After that, the workpiece is completely cut, whereupon—asdescribed above—also the sixth side can be machined.

[0010] It is true that the machine tool known from DE 196 35 258 C1allows machining of six sides of a workpiece, however, many intermediatesteps are necessary with the result that, on the one hand, machiningworkpieces is very time-consuming. Another disadvantage is that problemsin accuracy may occur by transferring the workpiece into a standardizedchuck, since the chuck is not adapted to the outer contour of theworkpiece.

[0011] Another disadvantage with the two machine tools described insofaris that they are very large-scale in design because two exactlyadjustable pivoting devices have to be provided, the first of whichallowing machining of the fifth side and the second one allowingmachining of the sixth side.

SUMMARY OF THE INVENTION

[0012] In view of the above, it is an object of the present invention toimprove the machine tool mentioned at the outset such that the speed andthe accuracy of machining are increased in a manner that is simple indesign

[0013] According to the invention, this object is achieved with themachine tool mentioned at the outset in that the device comprises amanipulator for positioning a gripper, by which gripper a workpiece isremovable that has been finished in the workpiece carrier, and aclamping station into which the gripper holding the workpiece can beinserted.

[0014] The object underlying the invention is in that way completelyachieved.

[0015] The inventors of the present invention have recognized, namely,that a manipulator, i.e. a kind of a robot arm, may be used fortransferring the finished workpiece, although both the accuracy ofpositioning and the holding forces of such manipulators are notsufficient for machining by means of a milling tool with the accuracydesired. For this reason, such manipulators have, up to now, not beenused for holding workpieces during machining. However, by means of theclamping station provided according to the invention, thesedisadvantages of the manipulator that is otherwise constructed in a verycost-effective and simple manner, can be remedied by clamping thegripper into the clamping station. This means that a clamping stationarranged in a predetermined adjustment provides accuracy as well as theholding forces required, while the pure handling is done by themanipulator.

[0016] In that manner, also the different intermediate steps can beavoided that are common for a 6-sides-machining in the prior art. Themanipulator grips the workpiece in any position, whereupon it can becompletely cut from the workpiece bar. After that, the manipulatorpivots the workpiece such as required for the next machining, and theninserts its gripper into the clamping station where it is suitablyclamped.

[0017] It is preferred herein if the manipulator comprises a beam thatis pivotable about a vertical axis, at which beam the gripper ispivotably mounted about a rotation axis that runs transversally withrespect to the vertical axis.

[0018] It is here advantageous that the workpiece can horizontally beremoved from the workpiece carrier in a simple manner. The gripper thenfirst pivots the workpiece by 90° and moves then laterally into theclamping station where it is locked. After the fifth side has beenmachined in this clamping, the gripper moves out of the clampingstation, turns the workpiece by 180°, and then enters the clampingstation again, so that now the sixth side can be machined.

[0019] In this manner, a 6-sides-machining is possible, without a pivotdrive being necessary for turning a workpiece clamped for machining by90° such that its front side can be machined.

[0020] It is further preferred if the beam is vertically adjustable intothe direction of the vertical axis.

[0021] This measure means a considerable advantage in time, since theworkpieces can also be vertically removed, so that pivoting back theclamping device prior to removing the workpiece can be omitted forworkpiece carriers with a pivot drive.

[0022] It is generally preferred if the clamping station comprisesclamping jaws for centering and holding the gripper, which clamping jawsare adapted to an outer contour of the gripper.

[0023] By means of this measure, considerable advantages in accuracy canbe achieved, since an exact centering and positioning of the gripper canbe provided in a reproducible manner by means of clamping jaws that areexactly adapted to the outer contour of the gripper. By means of thecontours adapted to each other, it is provided that the workpieceremains adjusted right in position even in quick chip removingmachining.

[0024] It is further preferred if the gripper comprises exchangeablejaws that are adapted to an outer contour of the workpiece. This measureincreases the accuracy even further, since the workpiece can be held ina considerably safer manner by adapted jaws than by standardized jaws.This measure has also advantages in design because in a transition tomachining a workpiece with another geometry, merely the jaws of thegripper need to be newly adapted, all other aggregates of the machinetool remain unchanged, without reduction in accuracy or speed ofmachining.

[0025] It is also generally preferred if the workpiece carrier comprisesa clamping device that is transversally pivotable with respect to thevertical axis, by which clamping device the workpiece can be broughtinto a vertical adjustment for machining of its side remote from theclamping device.

[0026] This measure already known from DE 196 35 258 C1 allows machiningof five sides in one single clamping. The manipulator grips, aftermachining the fifth side, the vertically aligned workpiece that is,subsequently, cut from the workpiece bar. After that, the manipulatorpivots to the clamping station, simultaneously turning the gripper by180°. In this position, the gripper is clamped into the clampingstation, whereupon now the sixth side of the workpiece points to the topso that it can be machined.

[0027] Further advantages can be taken from the description and theattached drawings.

[0028] It is to be understood that the features mentioned above andthose yet to be explained below can be used not only in the respectivecombinations indicated, but also in other combinations or in isolation,without leaving the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] An embodiment of the invention is shown in the drawings and willbe explained in more detail in the description below. In the drawings:

[0030]FIG. 1 shows a schematic side view of the new machine tool;

[0031]FIG. 2 shows a top view of the machine tool from FIG. 1, also in aschematic view;

[0032]FIG. 3 shows a representation like FIG. 2, but with a workpiecepivoted by 90°;

[0033]FIG. 4 shows a top view onto a gripper clamped in a clampingstation; and

[0034]FIG. 5 shows the gripper from FIG. 4 in isolated representation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] In FIG. 1, a machine tool very schematically shown and comprisinga machine bed 11, is generally designated with 10.

[0036] On machine bed 11, a moving column 12 is arranged at which aheadstock 14 is mounted. Headstock 14 can be positioned with referenceto machine bed 11 in the three directions in space in a common manner.

[0037] In headstock 14, a tool spindle 15 is rotary-driven mounted intowhich tools 16 can be inserted for machining a workpiece 18 that is heldin a workpiece carrier 19.

[0038] Workpiece carrier 19 comprises a clamping device 21 into whichworkpiece 18 is clamped. Clamping device 21 can be pivoted about a pivotaxis indicated in 22 such as indicated by an arrow 23. In the clampingshown in FIG. 1, workpiece 18 is being machined at its side 24 remotefrom clamping device 21.

[0039] Besides of workpiece carrier 193 a device 26 for removing andholding a workpiece 18 finished in clamping device 21 is arranged onmachine bed 11. This device 26 comprises a manipulator 27 that carries agripper 28 on its outer end. Behind manipulator 27, a clamping station29 is indicated into which gripper 28 can be clamped in a manner yet tobe described.

[0040] Finally, a deposit station 31 is indicated at the right side ofmanipulator 27 onto which manipulator 27 lays down finished workpieces18.

[0041] Manipulator 27 comprises a beam 33 that is mounted at an upright34 pivotable about a vertical axis 35 that runs transversally withrespect to pivot axis 22, as indicated by an arrow 36. Gripper 28 ismounted at beam 33 pivotable about a rotation axis 38 that runstransversally with respect to pivot axis 22 and with respect to verticalaxis 35, as is indicated by an arrow 39.

[0042]FIG. 2 shows the machine tool from FIG. 1 in a top view, whereinheadstock 14 and tool spindle 15 are merely indicated in dashes.

[0043] It can be seen in FIG. 2 that clamping device 21 is mounted at abase 41 at which also a motor 42 is provided for pivoting clampingdevice 21 about pivot axis 22.

[0044] Clamping station 29 comprises two clamping jaws 44 movabletowards each other, which clamping jaws each comprise in a directionfacing each other a curved surface 45 that is adapted in its contour toan outer contour of gripper 28 as indicated at 46.

[0045] A recess 47 is provided between clamping jaws 44, so that gripper28 can be put between clamping jaws 44, without a workpiece 18 thatpossibly protrudes to the bottom being moved and/or coming into contactwith a support surface 48 for clamping jaws 44.

[0046] Before clamping device 21 is pivoted into the position shown inFIG. 1 and 2 in which side 24 of workpiece 18 points to the top formachining, it is located in the position shown in FIG. 3, in whichlongitudinal sides 49 of workpiece 18 can be machined. It can be seen inFIG. 3 that workpiece 18 is part of a long workpiece bar that is pushed,step by step, through clamping device 21 from the left to the right.

[0047] In the position shown in FIG. 1, longitudinal sides 49 and frontside 24 of workpiece 18 have been machined so that it can now be cutfrom the workpiece bar.

[0048] To this end, manipulator 27 grips workpiece 18 with its gripper28, whereupon the tool shown in FIG. 1 that is a circular saw, then cutsworkpiece 18 from the remaining workpiece bar.

[0049] Manipulator 27 pivots then to the side into the direction ofarrow 36, rotating at the same time gripper 28 about rotation axis 38,so that front side 24 of workpiece 18 now points to the bottom.

[0050] As soon as gripper 28 has arrived over clamping station 29, it islowered between clamping jaws 44 which then move towards each other and,thus, unshiftably lock gripper 28. This situation is shown in FIG. 4 inan enlarged detail.

[0051] It can be seen in FIG. 4 that clamping jaws 44 engage at jaws 50of gripper 28 and center same and press same simultaneously onto supportsurface 48.

[0052] Jaws 50 comprise to this end a contour 51 that is adapted to theouter contour of workpiece 18. Contour 51 can be better seen in FIG. 5,where gripper 28 is shown without clamping station 29.

[0053] Returning to FIG. 4, another holding jaw 53 is shown in therethat can be used for even better centering and holding of gripper 28.

[0054] With 54, compressed air or pneumatic hoses are shown throughwhich jaws 50 of gripper 28 can be moved to-and-fro. The clamping forcesthat can be generated in that way are relatively low, but they aresufficient, however, for the workpiece not to change its position whilebeing positioned between clamping device 21 and clamping station 29. Assoon as gripper 28 is clamped into clamping station 29, clamping jaws 44now exert pressure onto jaws 50, whereby workpiece 18 is safely held injaws 50.

Therefore, what I claim, is:
 1. A machine tool, comprising a workpiececarrier for clamping a workpiece to be machined, a headstock mounting arotary-driven tool spindle adapted to clamp in tools for machining theworkpiece, a manipulator equipped with a gripper for gripping aworkpiece clamped into the workpiece carrier, and a clamping stationdesigned to clamp in the gripper with a workpiece hold by the gripper,said manipulator adapted for removing said workpiece from the workpiececarrier and inserting the gripper into the clamping station.
 2. Amachine tool as in claim 1, wherein the manipulator comprises a beampivotably arranged about a vertical axis, the beam mounting the gripperpivotably about a rotation axis, said rotation axis running transverselywith respect to the vertical axis.
 3. A machine tool as in claim 2,wherein the beam is vertically adjustable into the direction of thevertical axis.
 4. A machine tool as in claim 1, wherein the clampingstation comprises clamping jaws for centering and holding the gripper,which clamping jaws are adapted to an outer contour of the gripper.
 5. Amachine tool as in claim 3, wherein the clamping station comprisesclamping jaws for centering and holding the gripper, which clamping jawsare adapted to an outer contour of the gripper.
 6. A machine tool as inclaim 1, wherein the gripper comprises exchangeable jaws that areadapted to an outer contour of the workpiece.
 7. A machine tool as inclaim 2, wherein the gripper comprises exchangeable jaws that areadapted to an outer contour of the workpiece.
 8. A machine tool as inclaim 1, wherein the workpiece carrier comprises a clamping device thatis transversely pivotable with respect to the vertical axis, such thatthe clamping device can position the workpiece into an orientation formachining of its side remote from the clamping device.
 9. A machinetool, comprising a workpiece carrier for clamping a workpiece to bemachined, a headstock mounting a rotary-driven tool spindle to clamp intools for machining the workpiece, a manipulator equipped with agripper, said gripper comprising exchangeable jaws adapted to an outercontour of the workpiece for gripping the workpiece, and a clampingstation comprising clamping jaws for centering and holding the gripperwith a workpiece hold by the gripper, said manipulator adapting fortransferring said gripper between a position at the workpiece carrierand a position in the clamping station.
 10. A machine tool as in claim9, wherein the clamping jaws of the clamping station are adapted to anouter contour of the gripper.
 11. A machine tool, comprising a workpiececarrier for clamping a workpiece to be machined, a headstock mounting arotary-driven tool spindle to clamp in tools for machining theworkpieces, a manipulator equipped with a gripper for gripping aworkpiece clamped into the workpiece carrier, and a clamping stationcomprising clamping jaws adapted to an outer contour of the gripper,said manipulator adapted for transferring said gripper between theworkpiece carrier and the clamping station.
 12. A machine tool as inclaim 11, wherein the gripper comprises exchangeable jaws adapted to anouter contour of the workpiece.